Method and apparatus for correcting the position of a track



United States Patent Inventors Franz Plasser;

Josef Theurer, Johannesgasse 3, Vienna, Austria Appl. No. 729,093 FiledMay 14,1968 Patented Dec. 8, 1970 Priority May 22, 1967 Austria Nos.A4785/67 and A4784/67 METHOD AND APPARATUS FOR CORRECTING THE POSITIONOF A TRACK 28 Claims, 24 Drawing Figs.

US. Cl. 104/7, 1 104/8, 104/12 Int. Cl. EOIb 27/17, E01 b 3 3/02 Fieldof Search .t 104/7, 7(8), 8, l2

[56] References Cited UNITED STATES PATENTS 3,269,017 8/1966 Stewart104/12 3,401,642 9/ l 968 Fisher l04/8 3,459,136 8/1969 St. John [04/8Primary Examiner-Arthur L. La Point Assistant Examiner-:Richard A.Bertsch A;t0rney Kurt Kelman ABSTRACT: The position of a track iscorrected in two phases. In the first phase, the track is moved by atrack engaging means and this movement is terminated before the correcttrack position has been reached. The movement of the track to thecorrect position is then continued in a second phase solely by tampingthe ballast.

PATEN'TED nan 8I970 3.545; 384

SHEET 3 OF 3 INVENTORS BY MN @am BACKGROUND AND SUMMARY OF THE INVENTIONThe present invention relates to a method and apparatus for gradingand/or lining a track in relation to a reference system associated withat least one rail of the track. Such track correction is accomplished bymoving the track until the correct track position is indicated by anindicating element cooperating with a reference system, the indicatingelement moving in unison with the rail to be moved for correction.

A variety of machines of this type are known and comprise not only sucha reference system but also track correction means arranged forengagement with the rail and for moving the rail, and means for tampingthe rail to fix the same in the corrected position. The reference systemmay be constituted by reference lines, such as tensioned flexibleelongated members or beams of electromagnetic.radiation, i.e. wires orlight beams, but it may also consist of rigid parts, such as rods andthe like, whose position in relation to the track may be varied, ifdesired, in any predetermined manner.

In the conventional track grading and/or lining procedures, the trackengaging means were operated to move the track vertically and/orlaterally until the cooperating indicating element and reference systemindicated the correct track position to have been attained. At thispoint, a controlsignal was usually generated by the cooperation of thereference system with the indicating element to terminate the operationof the track engagingmeans.

During and/or after the track correction movement, the ballast wastamped at the point of correction to fix the track in the correctedposition. To assure a long lasting fixation of the track in itscorrected position, it is desirable to compact the ballast on which thetrack rests as densely as possible, requiring high tamping pressures.Such high-pressure ballast compaction tends to cause further movement ofthe track upwards or sidewards, depending on the direction of thetamping pressure. Thus, in the conventional procedure wherein theballast was tamped after the track had reached its corrected position,the additional tamping causedfurther movement of the track out of itscorrected position. In an effort to avoid this and thus to minimizefaulty track positioning, the tamping pressure was so controlled thatthe tools worked under less than maximally attainable pressures. This,on the other hand, unfavorably influenced ballast compaction andthusreduced the quality of the tamping since maximal tamping pressures,particularly in the final tamping phase, are desirable to obtain maximumcompaction of the ballast.

Attempts at such tamping pressure regulation have been on a been on ahit-and -miss basis since it is exceedingly difficult, if not impossibleto regulate the tamping pressure after the track position has beencorrected so as to avoid furthermovement of the track but still to keepit high enough to produce high-quality tamping. This regulation isparticularlydifficult since ballast density varies considerably fromtrack point to track point so that the same tamping pressure hasdifferent results at different points. a

This phenomenon holds for grading wherein the ballast is tampedunderneath the tie to fix the graded track in the correct position, suchcompaction causing the track to rise slightly under the pressure of thecompacted ballast, as well as for lining wherein the ballast is tampedonly on that side of the Y track from which it has been moved, suchballast compaction at one end of the track ties preventing the tendencyof the track to return to its original position after the track shiftingmeans has been released and the resiliency of the track would snap itback if this were not prevented by the compacted ballast at that side.

Thus, the tamping pressure selection and regulation has been a verydifiicult problem in conventional track grading and/or lining operationswherein the track is moved into its correct position by track correctionmeans and fixed in this position by tamping. Errors have resulted eitherin the tion is indicated. The movement of therail by the rail engaging,

direction of inaccurate track positioning due to excess tamping pressureor low quality of tamping due to low tamping pressure.

' It is a primary object of the present invention to avoid the above andother disadvantages, to utilize maximum tamping pressures in trackcorrection operations and to use these pressures to move the trackduring a final correction phase into the correct position without thearbitrary regulation of the tamping pressure at different track points.

The above and other objects are accomplished in accordance with thisinvention by moving the track rail, with which the reference system isassociated and with which the indicating element moving in unison withthe rail cooperates to indicate the correct track position, by railengaging means, terminating this movement before the correct trackposition has been reached, and continuing the movement of the railsolely by the tamping of the ballast until the correct track posi meansis terminated in response to a predetermined position of the indicatingelement in respect of the reference system.

In track grading and/or lining machines of the abovedescribed type, theinvention provides means responsive to a first predetermined position ofthe indicating element in respect of the reference system forterminating the movement of the rail by the track correction meansbefore the correct position of the track has been reached, and means foractuating the tamping means for moving the rail into the correctposition by tamping after the movement by the track correction means hasbeen terminated. Means responsive to a second predetermined position ofthe indicating element in respect of the reference system terminatesactuation of the tamping means, the second predetermined positionindicating the correct track position BRIEF DESCRIPTION OF DRAWING Theabove and other objects, advantages and features of the presentinvention will be better understood by reference to the followingdetailed description of certain now preferred embodiments thereof, givenfor purposes of illustration and not as a limitation, taken inconjunction with the accompanying drawing wherein:

FIG. 1 is a schematic side view of a track correction apparatusaccording to this invention;

FIG. 1a is a top view ofFIG. 1;

FIG. 2 is a side view of one embodiment of an indicating element of thereference system used in the apparatus;

' FIG. 2a is a front view of FIG. 2;

FIG. 3 shows a control circuit: actuated by a signal generated by theindicating element of Flg FIG. 2 for actuating the track grading andtamping means of the apparatus;

FIGS. 4 and 4a illustrate the practical advantage obtained by gradingwith the apparatus of FIGS. 2 and 3;

FIG. 5 schematically illustrates a reference system according to theinvention and using a vertically movable reference line;

FIG. 6schematically illustrates a reference system according to theinvention and using a spotboard;

FIG. 7 illustrates a detail of track correction means for laterallymoving the track in a lining operation;

FIG. 8 shows a control circuit actuated by the moving means of FIG. 7;and

FIGS. 9 to 13 show schematically in side, top and front views variousmodifications of a reference system according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The illustrated trackcorrection apparatus is designed to correct the vertical as wellas thelateral position of a track, ie. it is useful for track grading andlining. Conventional apparatus of this type includes a machine frame 1which is mounted on trucks 2 and 3 for mobility on rails 4, 4 of thetrack to be corrected. The track includes ties 5 supporting the rails onballast (not shown).

This conventional mobile track grading and lining machine has mounted onthe machine frame 1 any suitable means 6 for engaging the track railsand moving the same laterally at track point R. Laterally spacedoutwardly of the ends of the ties 5 and in lateral alignment with thetrack moving means 6 are a pair of ballast surface tampers 7, 7 whichare vertically adjustably mounted on the machine frame, one or the otherof these tampers being selectively moved into surface contact with theballast for tamping the opposite to the side towards which the track isto be moved. In this manner, tamping of the ballast by this one tamperwill effectively assist in moving the track in the opposite direction.

The front end of the machine frame carries a vertically adjustable tracklifting means 8 of generally conventional structure, which includes apair of rail gripping elements 9 for each rail. Tamping means 10, asshown, for instance, in our U.S. Pat. No. 3,372,651, is mounted adjacentthe lifting the lifting means to tamp pairs of ties 5 adjacent thegrading point and to fix the ties in the graded position.

The track position is corrected, i.e. the track is graded and/or lined,in relation to a reference system associated with at least one rail ofthe track until the correct position of the track is indicated by anindicating element cooperating with a reference element of the system. Avariety of such elements will be described hereinafter, includingreference elements consisting of beams of electromagnetic radiation,such as light beams, and tensioned flexible elongated members, such astensioned wires.

In the embodiment of FIGS. 1 and 1a, the reference system for lateralalignment by means of track moving means 6 includes two reference linesof different lengths, which may be considered as chords of an arc, i.e.a longer chord 11 and a shorter chord 12 which is half the length ofchord 11. The ordinates of the chords are compared at the measuringpoint M, and the track is moved at point R, i.e. at the forward end ofthe shorter chord 12 until the ordinate of chord 12 corresponds with aparameter obtained at this point from the ordinate of chord II. The endsof the reference chords are anchored to bogies 13, l4, l5 and 16 whichare coupled to machine frame 1 by means of telescoping rods or the like.

The reference system for vertical alignment or grading by means of tracklifting means 8,9 includes a reference line 17 which is associated withone of the rails and is parallel to the correct position of the rail toserve as a reference element in respect of which the rail is to begraded. The illustrated reference line is a beam of electromagneticradiation, such as light, which passes between sender (or receiver) 18and receiver (or sender) 20. The reference line cooperates with anindicating element 19 which is a spotboard movable in unison with therail into the path of the beam 17 to indicate the correct position ofthe rail.

As shown in FIG. la, the track liner may also carry an indicator 19aextending transversely of the track and showing the tracksuperelevation. Pendulum indicators of this type, for instance, are verywell known, and the track elevation is adjusted with such indicators byusing one rail of the track as the fixed reference in respect of whichthe other rail is lifted to determine the superelevation of the track.

In such an arrangement in accordance with the invention, the indicatormay so control the track lifting operation that the other rail is raisedonly by tamping.

The forward bogie 13, to which the forward end of long chord 11 isanchored and which carries also the forward end of the reference line17, is stationed in a track portion to be corrected. The indicatingelement 19 rests on a rod supported on a point of the track to becorrected whereby the element 19 moves in unison with the rail when thelatter is lifted by by hydraulically operated rail lifting means 8,9.When the top edge of element 19 enters the path of light beam 17, therail has reached its correct grade and this element may, therefore, beused as a signal generator to control the movement of the rail. The rearend 20 of reference line 17 is supported on a bogie 21 which rests on agraded portion of the track behind the tamping means 10.

All of the above-described structure is conventional and has, therefore,been shown and described only broadly for purposes of a betterunderstanding of the environment of the present invention.

FIGS. 2 and 2a and 3 show one embodiment of an indicating element and anassociated control circuit useful in the practice of this invention. Inthis embodiment, the indicating element is a spotboard having a fixedpart 22 which is mounted on a rod, as shown in FIG. 1, which issupported on rail 4 and moves upwardly towards reference element 17 inunison with the rail in the direction of the arrow shown in FIG. 2 whenthe rail is lifted by means 8,9. Fixed spotboard part 22 carries a part23 which is movable in respect thereto in the direction of movement ofthe spotboard, and which has an upper sensing edge for cooperation withthe beam 17. The sensing edge of movable part 23 may be moved upwardlyto be spaced adjustably from the upper edge of the fixed part 22 by adistance x. When the movable part has been extended in the illustratedmanner by distance x, the sensing edge of the movable part contacts beam17 first, whereupon the movable part may be retracted so that itssensing edge no longer extends above the upper edge of the fixed part,and the upper edge of the fixed part will then contact beam 17 as thespotboard moves further upwards in unison with the rail whereon it issupported and which is being graded. The movement of the movable part 23is hydraulically or pneumatically actuated in the illustratedembodiment, a pressure fluid cylinder 24 being mounted on the fixedspotboard part and a piston 25 moving in the cylinder and supporting themovable part.

Spotboards with an adjustable upper edge are also shown in our U.S. Pat.No. 3,363,582, and any such devices are useful for the presentinvention.

The control circuit for the track grading operation with the aid of thespotboard of FIG. 2 is shown in FIG. 3. The pressure fluid supply forthe pressure fluid motor 24, 25 is part of the pressure fluid circuitused for the operation of the hydraulically operated rail lifting means8, 9 and tamping means 10. At the beginning of the grading operation,control S opens valve 28 to deliver pressure fluid to hydraulic motor 26of the track lifting means and valve 29 to hydraulic motor 27 forreciprocating the tamping tools of tamping means 10. Thus, the rail islifted, tamping of the ties under the lifted rail is begun and,simultaneously, pressure fluid is also delivered to motor 24,25 toextend the movable part of this spotboard as it approaches the referencebeam-l7. As soon as the extended sensing edge of movable spotboard part23 contacts the beam, a first signal is generated and sent to receiver Ewhich signal is amplified by amplifier V, and the amplified signal issent to control S which includes a series of relays. This causes thecontrol S to close valve 28, thus interrupting the operation of thetrack lifting means before the rail has attained the correct grade.Simultaneously, control S reverses the flow of pressure fluid intocylinder 24, i.e. it delivers the fluid to the upper instead of thelower chamber, thus retracting the movable part 23 away from referencebeam 17. However, valve 29 remains open and the tamping means continuesto operate to tamp the ballast below the lifted ties of the track. Thistamping of the ballast causes the track to be raised further until theupper edge of the fixed spotboard part contacts beam 17 to generate asecond signal. Contact between the fixed upper edge of the spotboard andthe reference beam indicates that the rail has reached the correctgrade. The second signal is also received at E, amplified by V andoperates the relays of control S to close valve 29 and thus todiscontinue tamping.

As is well known, the hydraulic pressure may be used not only toreciprocate the opposing pairs of the tamping tools but also to vibratethem and to move the tamping tool carrier up and down to immerse thetools in the ballast and to remove them therefrom.

In the above described operation, the first grading phase is effectuatedby the rail lifting means until the firstsignal is generated, whereuponthe second grading phase begins to lift the rail by the distance x tothe correct grade only by means of tamping.

In FIG. 3, the full lines of the circuit show electrical control lineswhile the dash-dot lines indicate pressure fluid conduits.

The advantage of such a two-phase track correction operation isillustrated in FIGS. 4 and 4a, with FIG. 4 showing the conventionaloperation while FIG. 4a illustrates the grading operation according tothe present invention.

Conventionally, rail lifting means 9 were used to lift the rail 4 withties 5 the desired distance ain respect of reference line 17.Simultaneously and for a short period thereafter, tamping waseffectuated at 10 at a track point immediatelyadjacent the track liftingpoint. The hydraulically operated tamping tools reached their highestpressure and corresponding degree of ballast compaction towards the endof the operation when the ties had been lifted to the desired grade bylifting means 9. However, this strong compaction of the ballast forcedthe ties higher and above the desiredgrade so that the track received ahump indicated by the upwardly pointed arrow at the tamped tie.

In contrast thereto and as shown-in FIG. 4a, the rail is lifted in thefirst phase by lifting means 9 only by a distance xi, the remainingdistance x being covered in the second phase by tamping only so that thegraded rail will be accurately and evenly corrected in relation to thereference line 17 In the above-described embodiment, a part of theindicating element of the referencesyste m'is spaced from the referenceelement thereof after the first phase has been terminated, this spacingcorresponding to the distance x required to lift the track to thecorrect position solely by tamping. However, the same result may beaccomplished by spacing at least a portion of the reference element fromthe indicating element by this distance x so that a second controlsignal will be generated when the indicating element has risen in unisonwith the rail by that distance to the new level of the referenceelement. An embodiment of such a structure is shown in FIG. 5.

In this embodiment, too, the reference system includesan indicatingelement 19 and a cooperating reference element 17. The reference elementis a tensioned wire 17 trained over pulleys 30,30. A means 31 for movinga portion of the a reference line 17 in respect of the spotboard 19 ismounted adjacent each end of the reference line, the illustratedreference line moving means being a lever arm arranged to press againstthe tensioned wire in a direction opposite to that of the movement ofthe spotboard (see arrow). The lever arm 31 is pivoted against the wire17 by a hydraulic or pneumatic motor 32 when this motor is operated in amanner equivalent to that of motor 24,25 of FIG. 3, the lever arm 31.being normally held in the upper position shown in full lines by thebias of return spring 33.

If only a single lever is provided (for instance, the lever at the rightin FIG. 5), the tensioned wire will assume the inclined position 17ashown in broken lines when the lever is depressed. However, if theillustrated pair of levers is mounted adjacent each end of the tensionedwire, it will assume the depressed position shown in dash-dot lines at17b when both levers are moved down simultaneously. In either case, theportion of the reference element cooperating with indicating element 19is moved towards the indicating element by distance x. Contact betweenthe depressed reference element and the rising indicating elementgenerates the first signal in the same manner as described hereinabovein connection with FIG. 3, whereupon the reference element is raised bydistance x the second signal being generated upon contact of theindicating element 19 with the raised reference element to terminate thesecond grading phase.

Obviously, any other suitable means may be used to change the distancebetween the indicating element and the reference element. For instance.the pulleys could he vertically adjustably mounted so as to move thereference. line into selected distances from the indicating element.

FIG. 6 shows yet another embodiment of the present invention. In thisembodiment, the reference element is a sighting line 17 emanating fromsurveying instrument 18 mounted on front bogie 13. The sighting line 17is directed towards spotboard 34 which carries a series of superposedmarkers 35 each having a width corresponding to distance x. (For abetter illustration of this spotboard, it has also been shown in frontview in FIG. 6). The spotboard is glidably attached in bearings on thepressure fluid cylinder 8 of the lifting means, the piston in thecylinder carrying the rail engaging clamp 9. In this manner, theindicating element 34 moves in unison with the rail 4 when the same islifted, a lifting device of this type being shown, for instance, in ourUS. Pat. Nos. 2,847,943 or 3,146,727.

When the surveyor at instrument 18 projects the sighting line againstone marker 35, he discontinues the operation of hydraulic lifting motor8,9, and when the sighting line registers with the next marker, whichindicates the correct grade, tamping is discontinued, too. 20

Obviously, instrument 18 may be a sender of a beam of electromagneticradiation andthe markers may be photosensitive cells, for instance, sothat successive signals will be automatically generated in thepreviously described manner when the reference beam hits successivemarkers during the upward movement of the spotboard, as shown in FIG.13.

An embodiment of the invention showing the same applied to track liningis shown in FIGS. 7 and 8. The track alignment device hasbeen onlypartially shown since it is fully described in our US. Pat. No.3,3l4,373. It includes a transversely extending rotatable threaded shaft36 carrying a nut 37 which constitutes an indicating element movable inunison with the rail transversely of the track elongation, and whichcooperates with the reference line 12 (see I FIG. 1a). The nut has abifurcated portion 38 constituting sensing means on each side of thereference line to determine when the reference line is free of contactwith the sensing means, i.e. the desired alignment has beenaccomplished. No further description of this alignment method isrequired in view of the full description in our prior patent.

According to the present invention, the indicating element part 38 .ismovable in respect of the fixed indicating element part 37 by means ofhydraulic motor 39,40, being first extended forwardly by distance xtowards the reference line (see broken lines) in a manner quite similarto that described in connection with the grading method of FIG. 3. Inthis manner, a first signal is produced in the extended position of theindicating element sensing part and a second signal is generated in theretracted position of this part, the first signal causing termination ofthe operation of the track shifting means and the second signalterminating the tamping. In principle, therefore, lateral alignmentaccording to this invention operates in a the samemanner as verticalgrading, the difference being that the indicating element extends towardthe reference element ina horizontal plane transversely of the track forlining while it extends in a vertical plane perpendicularly to the trackfor grading, i.e. always in the direction of movement of the indicatingelement in unisonwith the rail whose position is to be corrected.

This analogous operation is shown in the circuit diagram of FIG. 8whichis similar to that of FIG. 3. In other words, the

, pressure. fluid supplyfor the pressure fluid motor 39,40 is part ofthe pressure fluid circuit (shown in dash-dot lines) used for operationof the hydraulically operated rail shifting means 6 and surface tampingmeans 7. At the beginning of the lining operation, control S opensvalves 44,45 and 46 to deliver pressure fluid to the hydraulic motor ofthe track shifting means 6 and to the vibrator of surface tamper 7,branch line 43 simultaneously delivering pressure fluid to hydraulicmotor 39,40 to with the forwardly extended bifurcated sensing part 38, afirst signal is generated and sent to receiver S which is amplified byamplifier V, and the amplified signal is sent to control S whichincludes a series of relays, the electrical circuit lines being shown infull lines. This causes the control S to close valve 45, thusinterrupting the operation of the track shifting means 6 before the railhas attained the correct alignment. Simultaneously, control S removesthe pressure from cylinder 39, thus permitting retraction of movablesensing part 38 under the bias of spring 42 away from reference line 12into the position shown in full lines in FIG. 7. However, valve 46remains open and the surface tamper continues to operate to tamp theballast next to the end of the tie, causing the track to be shiftedfurther (towards the right, as seen in FIG. 8) until the reference line12 is again out of contact with the retracted sensing part 38, whichindicates the correct alignment and generates a second signalterminating tamping, i.e. closing valve 46. Thus, the two-phasealignment proceeds in the same manner as the previouslydescribedtwo-phase grading, the second phase of the alignment beingeffectuated solely by tamping.

The side view of FIG. 9 and the top view of FIG. 10 show respectiveembodiments useful for grading and lining, wherein the reference systemincludes a plurality of successive reference elements cooperating with asingle indicating element moving in unison with the rail to becorrected.

In the grading arrangement of FIG. 9, two superposed reference beams l7,17 are spaced apart by distance x, each beam extending between a sender(or receiver) l8", l8 and a receiver (or sender) 20', 20, the ends 18,18 of the beam being at front bogie 13 while the ends 20, 20 are mountedon the machine frame 1. The spotboard 19 moves upwardly with rail 4,being glidably journaled at the front end of the frame. As shown inFIGS. 9a, 9b and 9c, the reference lines are superposed in the directionof movement of the indicating element 19 so that the sensing edge of theelement 19 will generate a first signal when it contacts-the lowerreference line and a second signal when it contacts the upper referenceline spaced from the lower line by distance x. The operation of thesesignals has been explained hereinabove. As shown in FIGS. 9b and 9c, thesuperposed reference lines may also be laterally staggered so that astepped edge of the indicating element reachcsfirst the one and then theother line, the distance x then being a function of the distance ybetween the reference lines and the distance z between the stepped edgeportions of the indicating element. Thus, referring to FIG. 9c, thedistance x between the reference lines is y-Z.

The identical conditions prevail in the lining arrangement of FIG. 10,except that the two reference lines are in a horizontal planetransversely of the track.

The modifications shown in FIGS. 11 and 12, with illustrative FIGS. Ila,11b and 110, as well as 1211, are substantially the same as those of thecorresponding FIGS. 9 and 10, except that the two reference lines areconstituted by different physical embodiments, i.e. line 17' is a lightbeam, as in the previously described embodiment, while line 17 is atensioned wire extending between pulleys 30,30, as in the embodiment ofFIG. 5. The operation of these modifications is obvious from the abovedescription.

While the method and apparatus have been described in connection with anumber of specific embodiments, it will be obvious to those skilled inthis art, particularly after benefiting from the present teaching, thatmany variations and modifications are possible without departing fromthe spirit and scope thereof. In principle, it deals with a trackgrading or lining operation wherein the track is moved by a trackengaging means in a first phase and is moved into the correct positionin a second phase solely by tamping. To terminate the operation of thetrack engaging means, a first signal is generated, and the tamping isdiscontinued in response to the second signal indicating that thecorrect track position has been reached.

For instance, the present invention is also useful in a method oflifting one rail in relation to the other rail by means of atransversely extending indicator of the superelevation, such asdisclosed in our US. Pat. Nos. 3,1 1 1,908 or 3,l26,640, for instance.In this case, the transverse indicator whose indicating element moves inunison with the other rail, which constitutes the fixed reference, isarranged to generate a first signal terminating the operation of therail lifting jack while the final phase of the rail lifting to thedesired grade is effectuated solely by tamping, this phase beingdiscontinued by a second signal in a manner analogous to that describedin connection with the illustrated embodiments.

We claim:

I. In a method of correcting the level of a track in relation to areference system associated with at least one rail of the track untilthe correct level is indicated by an indicating element cooperating withthe reference system, comprising the steps of engaging the rail with arail engaging means, and upwardly moving the rail with said means, theimprovement of terminating the movement of the rail by said means beforethe correct level has been reached, and continuing the movement of therail solely by tamping ballast under the rail until the indicatingelement indicates the correct level, the tamped ballast fixing the railat said level.

2. In the method of claim 1, wherein the movement of the rail by saidmeans is terminated in response to a predetermined position of theindicating element in respect of the reference system.

3. In the method of claim 2, wherein the indicating element is movedwith the rail in respect of the reference system, a first signal isgenerated in said predetermined position, said first signal actuates thetermination of the movement of the rail by said means, a second signalis generated when the correct level has been reached, and said secondsignal actuates the termination of the tamping.

4. In the method of claim 3, wherein the second signal is generated byanother predetermined position of said indicating element in respect ofthe reference system.

5. In the method of claim 3, wherein the second signal is generated by apredetermined position of a part of said indicating element in respectof the reference system.

6. In the method of claim 3, comprising the further step of spacing theindicating element from said predetermined position in respect of thereference system, the spacing corresponding to the distance ofcorrection to be effectuated solely by tamping.

7. In the method of claim 6, wherein the spacing is effectuatedsimultaneously with the production of the first signal.

8. In the method of claim 6, wherein the spacing is effectuated bymoving at least a part of the indicating element in respect of thereference system.

9. In the method of claim 6, wherein said spacing is effectuated bymoving at least a part of the reference system in respect of theindicating element.

10. In the method of claim I, wherein the reference system includes areference line and the indicating element cooperates with the referenceline, and the movement of the rail by said means is terminated when theindicating element moves with the rail into a first predeterminedposition in respect of the reference line, said first predeterminedposition deviating from the correct level by the distance by which therail is to be moved solely by tamping.

11. In an apparatus for correcting the level of a track, comprising areference system associated with at least one rail of the track, anindicating element cooperating with the reference system and moving inunison with the rail in respect of the reference system to indicate thelevel of the track, track correction means arranged for engagement withthe rail and for moving the rail, and means for tamping the rail to fixthe rail in the corrected position, the improvement of means responsiveto a first predetermined position of the indicating element in respectof the reference system for terminating the movement of the rail by thetrack correction means before the correct level of the track has beenreached, and means for actuating the tamping means for moving the railto said correct contact with said reference line.

correction means has been terminated.

12. In the apparatus of claim 11, further comprising means responsive toa second predeterminedposition of the indicating element in respect ofthe reference system for terminating the actuation of the tamping means,said second predetermined position indicating the correct trackposition.

13. In the apparatus of claim '12, wherein the indicating elementincludes a succession -of parts spaced apart in the direction ofmovement, of "the indicating element and cooperating with thereferencesystem for generating a succession of signals corresponding tosaid predetermined positions.

14. In the apparatus of claim 13, wherein said indicating element partsare photosensitive cells. r

15. In the apparatus of claim 13, wherein theindicating element partsare sensing edges and said reference system includes a reference linearranged for cooperation with said sensing edges.

16. In an apparatus for correcting the level of a track, comprising areference system'associatedwith at least one rail of the track, anindicating element cooperating with the reference system and moving inunison with the rail in respect of the reference system to indicate thelevel of the track, track correction means arranged for engagement withthe rail and for moving the rail, and means for tamping the railto fixthe rail in the corrected position, the improvement of means responsiveto a first predetermined position of the indicating element in respectof the reference system for terminating the movement of the rail by thetrack correction means before the correct level of the trackhas beenreached, meansjfor actuating thetamping means for moving the rail tosaid correct level by tamping after the movementof the rail by the trackcorrection means has been terminated, and means responsive to a secondpredetermined position of the indicating element in respect of thereference system for terminating the actuation of the tamping means,said second predetermined position indicating the correct track level,the indicating element including a-succession of sensing edges spacedapart in the direction of movement of the indicating element andcooperating with the'reference system for generating a succession ofsignals corresponding to said predetermined positions, said referencesystem including a reference line arranged for cooperation with saidsensing edges, and a first oneof said sensing edges being movable andgenerating a first one of said signals upon 17. In the apparatus ofclaim 16, wherein the indicating element comprises a fixed part carryingthe movable sensing edge for movement in the direction of the movementof the indicating element and perpendicularly to the sensing edges, andthe fixed indicating element part carries a second sensing edge parallelto the first sensing edge and arranged for cooperation with saidreference line when the first sensing edge has been moved in thedirection of movement of the indicating element behind the secondsensing edge.

18. In the apparatus of claim 17, further comprising a drive for movingthe movable sensing edge, said drive being actuindicating the elementsensing edge being part of said pressure fluid system, the pressurefluid operated actuationof thetrack correction means causing themovement of the movable sensing edge outwardly of the fixed part of theindicating element in the direction of movement of the indicatingelement,

and the contact of the first sensing edge with the reference linegenerating-a signal terminating the'actuation .or the track correctionmeans andcausing the 'movable sensing edge to be retracted inwardly ofthe second sensingedge on the fixed part of the indicating element.

21. In the apparatus of claim 11, wherein the reference system comprisesa succession of reference lines arranged in the direction of movement ofthe indicating element, said positions of the indicating element inrespect of the reference system being predetermined by the successivecooperation thereof with the successive reference lines.

22. In the apparatus of claim 21, wherein a first one of said referencelines in the direction of movement of the indicating element is a beamofelectromagnetic radiation, and a second one of said reference lines isa tensioned flexible elongated member.

23. In an apparatus for correcting the level of a track, comprising areferencesystem associated with at least one rail of the track, anindicating element cooperating with the reference system and moving inunison with the rail in respect of the reference system to indicate tlhelevel of the track, track correction means arrangedfor engagement withthe rail and for moving the rail, and means for tamping the rail to fixthe rail in the corrected position, the improvement of means responsiveto a first predetermined position of the indicating element in respectof the reference system for terminating the movement of the rail by thetrack correction means before the correct level of the track has beenreached, and means for ac tuating the tamping means for moving the railto said correct level by tamping after the movement of the rail by thetrack correction means has been terminated, the reference systemcomprising a succession of reference lines arranged in the direction ofmovement of the indicating element, said positions of the indicatingelement in respect of the reference system being predetermined by thesuccessive cooperation thereof with the successive reference lines, theindicating element carrying a succession of sensing edges staggered inthe direction of movement of the indicating element, and each of saidsensing edges is arranged to cooperatewith a successive one of saidreference lines during the movement of the indicating element.

24. In the apparatus of claim 111, wherein the reference system includes:a reference line having at least a portion movably spaced from theindicating element, said positions of the indicating'element in respectof the reference system being predetermined by the successivecooperation of the movable.

reference line portion withthe indicating element, successivecooperation of the indicating element and movable reference line portiongenerating successive signals to terminate actuation of the railengaging and of thetamping means.

25. In an apparatus for correcting the level of a track, comprising areferencesystem associated with at least one rail of the track, anindicating element cooperating with the reference system and moving inunison with the rail in respect of the reference systemto indicate thelevel of the track, track correction means arranged. for engagement withthe rail and for moving the rail, and means for tamping. the rail to fixthe rail in the corrected position, the improvement of meansresponsiveto a first predetermined position of the indicating 'elementinrespect of the reference system for terminating the movement of therailby the track correction means before the correct level of the trackhas been reached, means for actuating thetamping means for moving therail to said correct level by tamping after the movement of the rail bythe track correction flmeans has been terminated, the reference systemincluding a reference line having at least a portion movably spaced fromthe indicating element, said positions of the indicating'element inrespect of the reference system being predetermined by the successive.cooperation of the movable reference lineportion with the indicatingelement, successive cooperation of the indicating element and movablereference line portion generating successive signals to terminateactuation of the rail engaging and of the tamping means, and means formoving said reference line portion in respect of the indicating element,a first cooperation of said reference line portion with the indicatingelement generating said signal terminating the actuation of the trackcorrection, means and simultaneously causing the moving means to movethe reference line portion away and spaced from the indicating elementin the direction of movement of the indicating element, the referenceline being a tensioned flexible elongated member, and said moving meansbeing an arm arranged to press against the elongated member in adirection opposite to that of the movement of the indicating element.

26. In the apparatus of claim 11, wherein the indicating element is aspotboard carrying at least two markers, and the reference systemincludes a sighting line directed and ending at said spotboard, saidmarkers generating a first signal terminating the actuation of the trackcorrection means when the sighting line cooperates with a first one ofsaid markers, and a second signal terminating the actuation of thetamping means when the sighting line cooperates with a second one ofsaid markers indicating the correct track position.

27. In the apparatus of claim 26, said markers being photosensitivecells and said sighting line before a beam of electromagnetic radiation.t

28. In an apparatus for correcting the level of a track, comprising areference system associated with at least one rail of the track, anindicating element cooperating with the reference system and moving inunison with the rail in respect of the reference system to indicate thelevel of the track, track correction means arranged for engagement withthe rail and for moving the rail, and means for tamping the rail to fixthe rail in the corrected position, the improvement of means responsiveto a first predetermined position of the indicating element in respectof the reference system for terminating the movement of the rail by thetrack correction means before the correct level of the track has beenreached, and means for actuating the tamping means for moving the railto said correct level by tamping after the movement of the rail by thetrack correction means has been terminated, said indicating elementextending transversely of the track to indicate the tracksuperelevation, the reference system including one of the track rails inrespect of which the other track rail is to be moved into the correctposition

